The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is

The electric field of an electromagnetic wave in free space is given by $$\overrightarrow E = 10\cos ({10^7}t + kx)\widehat j\,\,V/m,$$ where t and x are in seconds and metres respectively. It can be inferred that
(1)  the wavelength $$\lambda $$ is 188.4 m.
(2)  the wave number k is 0.33 rad/m.
(3)  the wave amplitude is 10 V/m.
(4)  the wave is propagating along +x direction.

Which one of the following pairs of statements is correct ?

Which of the following statement is false for the properties of electromagnetic waves ?

The electric field part of an electromagnetic wave in a medium is represented by E_x = 0;

$${E_y} = 2.5{N \over C}\cos \left[ {\left( {2\pi \times {{10}^6}{{rad} \over m}} \right)t - \left( {\pi \times {{10}^{ - 2}}{{rad} \over s}} \right)x} \right];$$

E_z = 0.